FIELD OF THE INVENTION
In attempting to develop new technologies for economical storage of energy, the sodium/sulfur battery offers many advantages. The sodium/sulfur battery is rechargeable, has large storage capacity, and employs relatively inexpensive materials of low atomic weight, so that the storage capacity per unit weight is greater than heavier elements, such as lead.
While the sodium/sulfur battery offers many advantages, it also creates many new problems in developing an operable storage battery capable of numerous rechargings and dischargings at high efficiency. While aluminum, for many reasons, is a desirable container for the sulfur, aluminum forms sulfide layers with poor conductivity when exposed to sulfur/polysulfide melts. Since sulfur is nonconductive, electrical contact with the sulfur is achieved by using conductive carbon or graphite as mats and/or fibers. The conductive carbon or graphite fibrous material is substantially uniformly dispersed through the sulfur. Means must therefore be provided for allowing for efficient low resistance transmission of electricity from sulfur through the fibrous carbon and/or graphite to the aluminum container or other external electrical conductor. The means which provide the electrical transmission must not be subject to the formation of nonconductive or poorly conductive layers or contacts and must permit a mechanically and chemically stable contact.